Collaborative Research:RUI:P2C2: Extending Key Records of Holocene Climate Change and Glacier Fluctuations in the North Pacific Region Using Subfossil Wood from Southeastern Alaska

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This project aims to develop a multi-millennial, tree-ring chronology from subfossil trees exposed by retreating glaciers in Southeast Alaska to precisely calendar-date Holocene glacier fluctuations and compare them with a new record of climate seasonality. The multi-millennial tree-ring chronology will be used to extend reconstructions of spring and summer temperatures and build new records of winter storminess by analyzing traumatic resin ducts in annual tree rings. The winter storminess reconstruction is related to the strength of the Aleutian Low-pressure system (AL) and its analysis has the potential to transform the understanding of cold season ocean-atmospheric variability in the North Pacific. Specific goals of this project are to: 1) Generate 2,000-year-long records of wintertime AL along with summer temperature variability to determine how they responded to past climate forcing. 2) Use dendrochronology to precisely date when seven land-terminating and two tidewater glaciers advanced and retreated during the last 4000. 3) Test the hypothesis that the most extensive Holocene glacier advances in south coastal Alaska occurred when cooler summer air temperatures (reduced melt) coincided with a strengthened AL (increased snowfall). The potential Broader Impacts include the collection of time-sensitive archives of buried wood that would be available to the scientific communities for multi-disciplinary investigations. The project will generate new reconstructions of spring-summer temperature, winter storminess and glacier advance/retreats to better understand the dynamics of climate-glacier mass balance and the North Pacific decadal variability at millennial time scales. This project will provide training for four undergraduate students as part of their undergraduate thesis including field work, data analysis and presentation of the results. The researchers will engage in public outreach by giving two talks at Glacier Bay National Park. In addition, a dendrochronology workshop in partnership with the Hoonah Indian Association and the Hoonah Native Forest Partnership will be organized in the Native Alaskan Village of Hoonah with the goal of engaging students in skill-based technique centered on the collection and analysis of tree-ring records.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.